You can have selfish people that don't share their winnings with others, but who are nonetheless decent and would return another's wallet.

I'd point out selfishness has different dimensions.

When Chinese people get egoism and selfish behavior pointed out (in contexts where this could happen to soneome of any ethnicity) frequently they'll tell you it is oriented around their family and not their "self". That is a circle of concern bigger than your "self" but can also be an extension of the self and certainly can draw people away from being supportive of the community.

That's a bit vague, though. On the one hand, there is most definitely a prioritization of love and concern (close family comes before extended family, and onward, all the way up to the entire human species according to principles of subsidiarity), so you have a moral obligation to prioritize those closer to you, all else remaining equal.

But you don't get to intentionally (undesirable side effects can be permissible) commit evil acts against people of less concern (like robbing your neighbor to send your kid to college) for the sake of people of greater concern (or vice versa, of course). That's how the mafia operates. It's analogous to the difference between patriotism (the healthy and obligatory love of and concern for one's own nation) and chauvinism (the idolatrous and narcissistic "love" of one's own nation coupled with contempt and condescension for other nations).